Epson LQ-570e, Руководство по обслуживанию, Страница: 29 / 129

EPSON
LQ-570e/LQ-580
Revision
C
Product
Description
Interface
Specifications
29
1.4.4
Interface Selection
The
printer has 2 interfaces; the parallel interface and Type-B optional interface. These
interfaces
are selected manually by Default Setting or selected automatically.
o
Manual
Selection
One
of 2 interfaces can be selected by Default Setting.
o
Automatic
Selection
The
automatic interface selection is enabled by Default Setting. In this automatic
interface
selection mode, the printer is initialized to the idle state scanning which
interface
receives data when it is powered on. Then the interface that receives data
first
is selected. When the host stops data transfer and the printer is in stand-by
state
for the seconds specified by Default Setting, the printer is returned to the idle
state.
As long as the host sends data or the printer interface is in busy state, the
selected
interface is let as it is.
o
Interface
State and Interface Selection
When
the parallel interface is not selected, the interface gets into a busy state.
When
the Type-B serial interface card is installed and it is not selected, the
interface
sends XOFF and sets the DTR signal MARK. When the optional
interface
is not selected, the printer sets “OFFLINE” bit of MNSTS register to the
optional
interface.
When
the printer is initialized or returned to the idle state, the parallel interface got
into
a ready state, the serial interface sends XON and sets the DTR SPACE and the
printer
resets “OFFLINE” bit of MNSTS register to the optional interface. Caution
that
the interrupt signal such as a -INIT signal on the parallel interface is not
effective
while that interface is not selected.
1.4.5
Prevention Hosts from Data Transfer Time-out
Generally,
hosts abandons data transfer to peripherals when a peripheral is in busy state for
dozens
of seconds continuously. To prevent hosts from this kind of time-out, the printer
receives
data very slowly, several bytes per minute, even if the printer is in busy state. This
slowdown
is started when the rest of the input buffer becomes several hundreds of bytes. At
last,
when the input buffer is full, the printer is in busy state continuously.
1.4.6
IEEE1284.4 protocol
The
packet protocol described by IEEE1284.4 is supported on the parallel I/F.
Two
function modes of IEEE1284.4 protocol, “Off” and “Auto” are available, and one of
them
is selected according to the value of Default setting. (See 1.5.2.3 "Default Setting")
o
Auto:
Communication
is carried out in the conventional mode until a magic string
(1284.4
synchronous commands) is received. By receiving a magic string,
communication
in IEEE1284.4 packet mode is started.
o
Off:
Communication
is carried out in the conventional mode. A magic string (1284.4
synchronous
commands) is discarded.
NOTE: The
packet protocol of IEEE1284.4 allows a device to carry on multiple
exchanges
or conversations which contain data and/or control
information
with another device at the same time across a single point-
to-point
link.
The
protocol is not, however, a device control language. It does provide
basic
transport-level flow control and multiplexing services.
The
multiplexed logical channels are independent of each and blocking
of
one has no effect on the others. The protocol operates over IEEE1284.
1.4.7
Type-B Interface communication specification
o
Reply
for Optional Commands
Table
1-26. Reply for Optional Command
Option
Command
Number
Command
Name
Reply-A Reply-B
00h No-operation -- --
01h Start
Hardware Reset
Accept* Execute
OK*
02h Start
Software Reset
Reject --
03h Send
Main System Type
Accept Execute
OK
04h Send
Name Data
Reject --
05h Inquire
Name Data
Accept Execute
OK
06h Send
Product Name
Accept Execute
OK
07h Send
Software Emulation Type
Accept Execute
OK
08h Complete
Buffered Data
Accept Execute
OK
09h Stop
Procedure
Reject --